From: Eric Dumazet <edumazet@xxxxxxxxxx> Date: Mon, 23 Mar 2020 11:45:48 -0700 > On Mon, Mar 23, 2020 at 11:18 AM Kuniyuki Iwashima <kuniyu@xxxxxxxxxxxx> wrote: > > > > The refcounted is initialised at most three times. > > > > - __inet_lookup_skb() sets it true. > > - skb_steal_sock() is false and __inet_lookup() sets it true. > > - __inet_lookup_established() is false and __inet_lookup() sets it false. > > > > We do not need to initialise refcounted again and again, so we should do > > it just before return. > > > > Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxxxx> > > --- > > Well, I do not believe this patch (and the following one) makes things > more readable. > > I doubt setting a boolean in a register or a stack variable has any cost, > I prefer letting the compiler optimize this. > > The ehash lookup cost is at least 2 or 3 cache lines, this is the > major contribution. I confirmed that GCC (v7.3.1) does not make any change with this patch, but the original code is bit confusing. I think this patch makes the code bit more readable so that someone (like me...) will not doubt about complier optimization and write patches. I will respin only this patch because the changelog can be incorrect by complier optimization. Thanks.
